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Wednesday, Oct 03, 2018

Looking through a climate lens optimizes design

Optimizing pump design saves electricity use

The climate is changing. World leaders have, for the most part, accepted this fact and are committed to working together to stem rising global temperatures. In November 2015, 195 countries, including Canada, signed the Paris Agreement, pledging to cut emissions by 30% from 2005 levels by the year 2030. 

In support of these commitments and to assist in quantifying emission reductions by 2030, Infrastructure Canada recently published Climate Lens, a guidance document outlining the new assessment requirements for a range of large (≥$10 million), federally funded projects. The first of the two main components of Climate Lens is performing greenhouse gas (GHG) mitigation assessments, which measure the anticipated direct and indirect emissions impact of an infrastructure project. For example, direct emissions from water treatment processes can be estimated, as well as indirect emissions from the electricity purchased to operate these processes.  

The second requirement is for climate change resilience assessments, which employ a risk management approach to anticipate, prevent, withstand, respond to, and recover from a climate-change-related disruptions or impacts. For example, we can identify risks and resilience solutions to the increasing variability of water quality due to extreme events, such as floods, and from incremental events, such as increased temperatures and drought conditions. The goal of Climate Lens is facilitating climate-focused behavioural change at the project level, considering mitigation and adaptation needs. 

Low profile PVC underdrain

Within the context of the design and operation of water treatment plants and their processes, the benefits of climate resiliency and mitigation go beyond minimizing risks. Certainly, reducing the risk of failure of critical infrastructure has benefits from social, environmental, and economic perspectives. However, additional benefits to consider and strive for include improved performance of the built structures, ancillary systems, and treatment processes, as well as reductions in operating and maintenance costs. Implementing sustainable building design principles to new or retrofit water treatment plant buildings provides opportunities to adapt to the changing climate, for example, by considering changing heating and cooling needs, increased snow loads, and rising flood levels. Opportunities for mitigation are numerous and often fairly simple to incorporate with thoughtful planning. Examples include building siting and orientation to maximize daylighting, energy-efficient lighting sources, building envelope materials to improve insulation, passive ventilation, heat recovery, and water-efficient fixtures. These examples also represent cost savings in operation and maintenance of the facilities. 

Robust water treatment processes designed and optimized for resiliency to extreme and incremental climate impacts are generally expected to perform better and more consistently, while also leading to savings in operation and maintenance costs. For example, pumping typically contributes the highest proportion of a water treatment plant’s electricity usage. Electricity usage can be reduced by optimizing pumping through evaluation of pump sizing, installation of a variable frequency drive or on-site pump testing to confirm the best efficiency point. 

Jar testing helps to optimize chemicals required for treatment

Optimization of treatment processes leads to improved and more consistent performance and water quality, while also providing opportunities for savings in electricity, reduction in chemical usage, and minimization of generated process residuals (wastes). Identifying these opportunities typically represents a relatively low cost, but high value. For example, simple jar testing can assist with pre-treatment optimization of coagulant chemicals and mixing conditions to reduce dosages. Pilot-testing filter media ahead of replacement can identify the best performing and most productive media bed design based on site specific conditions. Computational fluid dynamic desktop analysis of primary disinfection can identify opportunities to reduce dosages and increase contact time through operational modifications, improved mixing or the addition of baffles.

Looking at the design and operation of water treatment plants through a ‘climate lens’ provides resiliency, reduces risks, and mitigates emissions, and also leads to opportunities to optimize performance and reduce life-cycle costs.

Associated Engineering’s climate scientists and engineers can assist clients with climate change projections, climate change resiliency assessments, and development of mitigation and adaptation measures in support of Climate Lens requirements.  For more information, contact Dr. Anna Comerton.

About the Author:  Based in our Toronto area office, Anna has 15 years of experience specializing in water treatment plant planning, assessment, optimization, and studies. Her experience also includes process design, facilities design, and project management of water treatment plants, pump stations, and reservoirs. Anna is a member of Associated Engineering’s Climate Change Advisory Group, which provides advice to clients and staff on climate change mitigation and resilience on infrastructure projects.